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Dogs may have arrived in the Americas only about 10,000 years ago, thousands of years after humans first did, researchers say.

This finding might shed light on patterns of human migration into the New World, scientists added.

In the study, the researchers looked at DNA from 42 new samples taken from ancient dog remains and compared that DNA with 42 other genetic samples from prior studies. The scientists discovered four never-before-seen genetic signatures in the new samples, suggesting there was greater diversity among the ancient dogs in the Americas than previously thought.

The most surprising finding, the researchers said, was that that dogs may have arrived in the Americas only about 10,000 years ago. This date "is about the same time as the oldest dog burial found in the Americas," study co-author Ripan Malhi, of the University of Illinois at Urbana-Champaign, said in a statement. "This may not be a coincidence."

The long history between humans and dogs makes canines a window into human history, giving insight on ancient patterns of migrations, for example, the researchers said. The new finding suggests that dogs came to the Americas with a second wave of human migration, thousands of years after people first traveled to the Americas from Asia.

"Dogs are one of the earliest organisms to have migrated with humans to every continent, and I think that says a lot about the relationship dogs have had with humans," lead study author Kelsey Witt, a biologist at the University of Illinois at Urbana-Champaign, said in a statement. "They can be a powerful tool when you're looking at how human populations have moved around over time." [10 Things You Didn't Know About Dogs]

The scientists detailed their findings online Dec. 18 in the Journal of Human Evolution.